Developing device, process unit, and image forming apparatus developer

Abstract

A black developer is conveyed in a first conveyance chamber in a rotation axis direction while agitating with rotation of a first screw member. A black-toner-concentration detecting sensor detects a toner concentration of the black developer by having contact with the black developer conveyed inside the first conveyance chamber. An average of peak amounts of a pressing force on the black developer, which is conveyed inside the first conveyance chamber by the first screw member, with respect to the black toner-concentration detecting sensor is set within a range of 9.8 15 [N/m 2 ] to 9.8 100 [N/m 2 ].

1. A developing device comprising:
 a developer conveying device configured to convey a developer containing a toner and a carrier; and 
 a developer holding unit configured to convey the developer conveyed by the developer conveying device to an area facing a latent-image holding unit in accordance with its own surface movement by holding the developer on its own endlessly-moving surface, and develop a latent image held by the latent-image holding unit, wherein 
 the developer conveying device includes:
 a developer conveying unit configured to convey a developer containing a toner and a carrier in a rotation axis direction while agitating the developer with rotation of an agitation conveying member, and 
 a toner-concentration detecting unit configured to detect a toner concentration of the developer by having contact with the developer conveyed inside the developer conveying unit or facing the developer via a wall of the developer conveying unit; and 
 
 an average of maximum amounts of a pressing force on the developer, which is conveyed inside the developer conveying unit by the agitation conveying member, by each one rotation of the agitation conveying member with respect to the toner-concentration detecting unit or an average of maximum amounts of a pressing force on the developer by each one rotation of the agitation conveying member with respect to a portion of the wall facing the toner-concentration detecting unit is set within a range of 9.8×15 [N/m 2 ] to 9.8×100 [N/m 2 ]. 
 
   
   
     2. The developing device according to  claim 1 , wherein the average of the maximum amounts is set at 9.8×25 [N/m 2 ] or more. 
   
   
     3. The developing device according to  claim 1 , wherein
 a screw member configured to convey the developer in the rotation axis direction while agitating the developer due to rotation of a spiral blade provided on a perimeter surface of a rotatably-supported rotating shaft member in a spirally-protruding manner is used as the agitation conveying member, and 
 the toner-concentration detecting unit is arranged in a position in which a toner-concentration detecting surface is extended to a surface direction perpendicular to the rotation axis direction. 
 
   
   
     4. The developing device according to  claim 1 , wherein a developer-conveying speed in a toner-concentration detecting area where the toner-concentration detecting unit detects the toner concentration, which is a portion of a whole area of the developer conveying unit, is slowed down as compared with a developer-conveying speed in other areas. 
   
   
     5. The developing device according to  claim 4 , wherein in the agitation conveying member developer-conveying performance in a portion corresponding to the toner-concentration detecting area, which is a portion of a whole area of the agitation conveying member in the rotation axis direction, is lowered as compared with a developer-conveying performance in other portions. 
   
   
     6. A process unit that is integrally attached to a main body of an image forming apparatus including a latent-image holding unit configured to hold a latent image, a developing device configured to develop the latent image held on the latent-image holding unit, and a transfer unit configured to transfer a visualized image developed on the latent-image holding unit onto a transferred member, wherein
 at least the latent-image holding unit and the developing device are held, as one unit, in a common holding unit of the process unit and the image forming apparatus, and 
 the developing device according to  claim 1  is used as the developing device. 
 
   
   
     7. The process unit according to  claim 6 , wherein the average of the maximum amounts is set at 9.8×25 [N/m 2 ] or more. 
   
   
     8. The process unit according to  claim 6 , wherein
 a screw member configured to convey the developer in the rotation axis direction while agitating the developer due to rotation of a spiral blade provided on a perimeter surface of a rotatably-supported rotating shaft member in a spirally-protruding manner is used as the agitation conveying member, and 
 the toner-concentration detecting unit is arranged in a position in which a toner-concentration detecting surface is extended to a surface direction perpendicular to the rotation axis direction. 
 
   
   
     9. The process unit according to  claim 6 , wherein a developer-conveying speed in a toner-concentration detecting area where the toner-concentration detecting unit detects the toner concentration, which is a portion of a whole area of the developer conveying unit, is slowed down as compared with a developer-conveying speed in other areas. 
   
   
     10. The process unit according to  claim 9 , wherein in the agitation conveying member developer-conveying performance in a portion corresponding to the toner-concentration detecting area, which is a portion of a whole area of the agitation conveying member in the rotation axis direction, is lowered as compared with a developer-conveying performance in other portions. 
   
   
     11. An image forming apparatus comprising:
 a latent-image holding unit configured to hold a latent image; and 
 a developing device configured to develop the latent image held on the latent-image holding unit, wherein 
 the developing device according to  claim 1  is used as the developing device. 
 
   
   
     12. The image forming apparatus according to  claim 11 , wherein the average of the maximum amounts is set at 9.8×25 [N/m 2 ] or more. 
   
   
     13. The image forming apparatus according to  claim 11 , wherein
 a screw member configured to convey the developer in the rotation axis direction while agitating the developer due to rotation of a spiral blade provided on a perimeter surface of a rotatably-supported rotating shaft member in a spirally-protruding manner is used as the agitation conveying member, and 
 the toner-concentration detecting unit is arranged in a position in which a toner-concentration detecting surface is extended to a surface direction perpendicular to the rotation axis direction. 
 
   
   
     14. The image forming apparatus according to  claim 11 , wherein a developer-conveying speed in a toner-concentration detecting area where the toner-concentration detecting unit detects the toner concentration, which is a portion of a whole area of the developer conveying unit, is slowed down as compared with a developer-conveying speed in other areas. 
   
   
     15. The image forming apparatus according to  claim 14 , in the agitation conveying member developer-conveying performance in a portion corresponding to the toner-concentration detecting area, which is a portion of a whole area of the agitation conveying member in the rotation axis direction, is lowered as compared with a developer-conveying performance in other portions.